@Ghost
There are a couple sources of information out there. The Flash Wiki (http://flashgordon.wikia.com/wiki/Flash_Gordon_Wiki) has lots of topics covered, but very limited information, whereas old Wikipedia (https://en.wikipedia.org/wiki/Flash_Gordon) has a few topics with lots of information and it includes separation between Raymond's version, and other versions. The Flash Wiki is lacking this, I think it went up around the time of the Sci Fi Chan series, and was never touched again. The comic strip still runs (http://flashgordon.com/), and their site contains the 1996 run through present (still weekly).
If I could find more information, would be good to cut and paste. I don't think its out there. Plus what @Ataru indicated. Its interesting enough that it can be played around with quite a lot.
In fact that is more spot on what I was thinking. There are a few basics that carry over throughout the genre of Flash.
Mongo is a feudal realm of mixed technology, primitive to highly advanced (atomic retro advanced). The realms are all ruled by Kings/Queens. The main realms are: Arboria (Prince Barin, Timothy Dalton and Richard O'Brien), Sky City (Hawkmen, Brian Blessed), Nascent City or Ming's City and Palace, and at least two other big ones not in most movies, Frigia the snow realm, and the Land of the Lion men.
I think they can be expanded; take the Lion Men, they just live in tents and fly Sky Gyro aircraft things originally. In the later run (Jeff, on the comic strip website), they have bigger structures and more underground areas where the resistance gathers safely.
There is a bit of work to bring it up to date (ideologically, but keeping atomic retro sci fi feel), and a lot of realms to explore. The basics are always there, mentioned above, but there is so much more room. They always show other races on the planet from various lizard men to saurens (dinosaur features ones), and other odd aliens as background. Almost a determination process, where a few individuals would be better to make, vote, approve adding something versus one persons view of what this could be, and in realizing the depth of work to make it breathing, living, cohesive is what led me to advertise on the boards here.
An individual would be swamped, but a few individuals taking an area each. Working a little, getting feed back, seeing the other areas and balancing it out as they go, would do wonders to complete the setting.
And at the heart, it is settling on exactly the focus of play on a regular basis. An arc to overthrow Ming is good, but been done, and will end sooner than it began, but some system of sustainable play would be good (ie, start with Ming, but overthrow and move into feudal rule and who actually rules the planet). All things group worthy.
Maybe I'll just put thoughts up here for input and write to the wiki as decisions or some consensus comes up. I have ideas that would be fun for updating each realm, but its limited to my thoughts and as already scene, everyone has a different take on Flash; from Defenders of Earth to the Sam Jones movie.